<html>
<head>
<title>无标题文档</title>
<script language="javascript">
       
    var level = 1;
    var div      ;
    var timeout  ;     

    document.onclick = function (event){
        var e     = event || window.event ;
        div = document.getElementById('mydiv'); 
        level = 1;
        if(level === 1){
            div.style.marginLeft = e.clientX;
            div.style.marginTop  = e.clientY;  
            div.style.width      =  '0px';
            div.style.height     =  '0px';
            clearTimeout(timeout);
        } 

        var step = function (){  
            var width  =  parseInt(div.style.width.substring(0,div.style.width.length -2)) ;
            var height =  parseInt(div.style.height.substring(0,div.style.height.length -2));
            
            var left   =  parseInt(div.style.marginLeft.substring(0,div.style.marginLeft.length-2));
            var top    =  parseInt(div.style.marginTop.substring(0,div.style.marginTop.length-2));
            
            div.style.width  = (width +  4 ) + 'px';
            div.style.height = (height + 2 ) + 'px';

            div.style.marginLeft = (left - (width+4) /2 +width/2)  + 'px'; 
            div.style.marginTop  = (top  - (height+2)/2 +height/2) + 'px';
            if(level <= 50){       
                level = level +1 ;
                timeout= setTimeout(step,100);
            }
        
        }
       timeout = setTimeout(step,10);
    }
 
</script>

</head>

<body>
 
<div id="mydiv" style="background-color:#99FF00;width:0px;height:0px; position:absolute;"></div>
 
 <div id='d'></div>
</body>
</html>